RESUMEN
A metallic core holder, fabricated from non-magnetic Hastelloy-C276, has been designed for Magnetic Resonance (MR) and Magnetic Resonance Imaging (MRI) of core plug samples at high pressures and temperatures. Core plug samples, 1.5â³ in diameter and 2â³ in length, can be tested in the core holder at elevated pressures and temperatures, up to 5000 psi and 80 °C. These are conditions commonly found in petroleum reservoirs. A radio frequency probe, which excites and detects magnetic resonance signals, was placed inside the metal vessel. Proximity to the sample improves the signal to noise ratio of the resulting measurements. The metallic core holder is positioned between the poles of a 0.2 T permanent magnet and subjected to rapidly switched magnetic field gradients as part of the imaging process. This switching induces eddy currents on the conductive core holder, which degrades the magnetic field gradient waveform in the sample space. The low electrical-conductivity of Hastelloy-C276 minimizes the duration and the magnitude of such eddy currents. A recently developed pre-equalization technique was employed to ensure that magnetic field gradient pulses, required for MRI, are near ideal in the sample space. A representative core flooding experiment was undertaken in conjunction with MR/MRI measurements.
Asunto(s)
Hepatitis C/terapia , Linfoma/terapia , Linfoma/virología , Mieloma Múltiple/terapia , Mieloma Múltiple/virología , Anciano , Femenino , Trasplante de Células Madre Hematopoyéticas/efectos adversos , Hepacivirus , Hepatitis C/sangre , Humanos , Linfoma/sangre , Masculino , Persona de Mediana Edad , Mieloma Múltiple/sangre , Prevalencia , Modelos de Riesgos Proporcionales , Estudios Retrospectivos , Factores de Riesgo , Trasplante de Células Madre , Tasa de Supervivencia , Trasplante Autólogo , Resultado del Tratamiento , Carga ViralAsunto(s)
Amiloidosis , Trasplante de Células Madre Hematopoyéticas , Cadenas lambda de Inmunoglobulina/sangre , Enfermedades Renales , Adulto , Anciano , Amiloidosis/sangre , Amiloidosis/complicaciones , Amiloidosis/mortalidad , Amiloidosis/terapia , Autoinjertos , Supervivencia sin Enfermedad , Femenino , Estudios de Seguimiento , Humanos , Enfermedades Renales/sangre , Enfermedades Renales/complicaciones , Enfermedades Renales/mortalidad , Enfermedades Renales/terapia , Masculino , Persona de Mediana Edad , Tasa de SupervivenciaRESUMEN
Nephropathy due to BK virus (BKV) infection is an evolving challenge in patients undergoing hematopoietic stem cell transplantation (HSCT). We hypothesized that BKV infection was a marker of kidney function decline and a poor prognostic factor in HSCT recipients who experience this complication. In this retrospective study, we analyzed all patients who underwent their first allogeneic HSCT at our institution between 2004 and 2012. We evaluated the incidence of persistent kidney function decline, which was defined as a confirmed reduction in estimated glomerular filtration rate of at least 25% from baseline using the Chronic Kidney Disease Epidemiology equation. Cox proportional hazard regression was used to model the cause-specific hazard of kidney function decline, and the Fine-Gray method was used to account for the competing risks of death. Among 2477 recipients of a first allogeneic HSCT, BK viruria was detected in 25% (n = 629) and kidney function decline in 944 (38.1%). On multivariate analysis, after adjusting for age, sex, acute graft-versus-host disease (GVHD), chronic GVHD, preparative conditioning regimen, and graft source, BK viruria remained a significant risk factor for kidney function decline (p < 0.001). In addition, patients with BKV infection and kidney function decline experienced worse overall survival. After allogeneic HSCT, BKV infection was strongly and independently associated with subsequent kidney function decline and worse patient survival after HSCT.